A mobile communications apparatus may include integrated circuit (IC) devices that use high-speed digital interconnects to communicate between or within certain IC devices. For example, a cellular telephone may include high-speed digital interconnects to support communication between radio frequency (RF) and baseband modem chipsets. High-speed digital interconnects may be used to transport data, control information or both data and control information between different functional components of an apparatus. Serial interfaces have become the preferred method for digital communication between IC devices in various apparatus. For example, a communications apparatus may use a high speed digital interconnect between RF and baseband modem chipsets. Mobile communications devices may perform certain functions and provide capabilities using IC devices that include RF transceivers, cameras, display systems, user interfaces, controllers, storage, and the like. General-purpose serial interfaces known in the industry, including the Inter-Integrated Circuit (I2C or I2C) serial bus and its derivatives and alternatives, including interfaces defined by the Mobile Industry Processor Interface (MIPI) Alliance, such as the I3C interface and the radio frequency front-end (RFFE) interface. Some standardized interfaces and proprietary interfaces may be applicable for use in coupling certain components of mobile communications equipment and may be optimized to meet certain requirements of the mobile communications equipment.
In one example, the I2C serial bus is a serial single-ended computer bus that was intended for use in connecting low-speed peripherals to a processor. Some interfaces provide multi-master busses in which two or more devices can serve as a bus master for different messages transmitted on the serial bus. In another example, the RFFE interface defines a communication interface for controlling various radio frequency front-end devices, including power amplifier (PA), low-noise amplifiers (LNAs), antenna tuners, filters, sensors, power management devices, switches, etc. These devices may be collocated in a single integrated circuit (IC) or provided in multiple IC devices. In a mobile communications device, multiple antennas and radio transceivers may support multiple concurrent RF links. Certain functions can be shared among the front-end devices and the RFFE interface enables concurrent and/or parallel operation of transceivers using multi-master, multi-slave configurations.
As the demand for improved communications between devices continues to increase, there exists a need for improvements in protocols and methods for managing the interfaces between RF front-end devices. For example, device synchronization can be problematic when, for example, RF devices are required to meet strict timing specifications in a multiple access RF network. Implementing global synchronization can be difficult and costly. Synchronization implemented using existing bus protocols to transfer system timer information may result in high-latency and high degrees of uncertainty.